French revolution in quantum photonics

Embargoed until: Publicly released: 2016-03-08 03:00

A French-Australian team has cleared a decades-long roadblock away, developing a single photon source that is a million times smaller in volume, and 20 times brighter, than existing sources. The new sources use quantum-dots - artificial atoms made of 10,000 or so semiconductor atoms - sandwiched between two microscopic mirrors that are housed inside a pillar a tenth the thickness of the finest human hair.

Media Release

Photonics, the technology that powers the global internet, uses bright lasers to function.

Quantum photonics will allow currently impossible capabilities in not only communication, but in sensing, metrology, and even computation, however it requires single particles of light—photons.

The problem is that to date there have been only approximate single-photon sources: these are physically large and hard to multiplex—making 6 independent photons at a time currently occurs at a lower rate than gravitational-wave detection!

A French-Australian team has cleared this decades-long roadblock away, developing a single photon source that is a million times smaller in volume, and 20 times brighter, than existing sources.

The new sources use quantum-dots—artificial atoms made of 10,000 or so semiconductor atoms—sandwiched between two microscopic mirrors that are housed inside a pillar a tenth the thickness of the finest human hair.

“The source is so bright because we use the mirrors to engineer the quantum vacuum, making the quantum-dot very likely to emit light in one direction, unlike natural light sources that emit light in all directions”, said Professor Pascale Senellart, lead of the team at the Centre National de la Recherche Scientifique, Paris.

“We have developed a technique that uses electric fields to ensure that the dot emits light at exactly the right colour for the mirrors it lies between”, she continues.

The new sources are a remarkable improvement over the current state-of-the-art sources, which use millimetre scale crystals, require expensive detectors to flag photon production, and mostly produce no light at all.

“The last twenty years have seen many proposals for exciting future technologies, all of which assumed single photon sources”, notes Juan Loredo, PhD student in the team at the University of Queensland, Brisbane, “We think the new devices will have the same effect in quantum photonics as moving from room-sized mainframes to personal computers did in computing”.

“These sources are the first scalable single-photon technology: literally, the future is looking bright”.

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French revolution in photonic technology

This image represents three sources of single photons: represented by a red dot at the center of the cavity, the semiconductor quantum dot (of nanometric size) is inserted in the center of the cavity, which consists of a 3 µm pillar connected to a circular frame by guides that are 1.3 µm wide. By applying electrical voltage to the cavity, the wavelength of the emitted photons can be tuned and the charge noise totally eliminated.